Do I need to fire caulk the panel penetrations through the top plate?
Almost always yes, but the requirement comes from two different places depending on the wall. NEC 2023 300.21 requires openings around electrical penetrations through fire resistance rated walls, partitions, floors, or ceilings to be firestopped using approved methods that maintain the rating. Separately, the building code requires fireblocking in ordinary wood framed walls even when nothing is fire rated.
Rated assembly or not?
If the panel wall is part of a rated assembly, such as the garage to house separation in some jurisdictions, a unit separation wall in a duplex or townhouse, or any commercial rated partition, then 300.21 applies directly and you need a listed firestop system: intumescent caulk or putty installed per the tested system details around every cable and conduit penetration.
Fireblocking in ordinary walls
In a standard dwelling wall, the IRC (R302.11) requires fireblocking at concealed draft openings, including at the top plate where cables and conduits pass from the stud bay into the attic or floor cavity above. The gap around a bundle of NM cables through a bored top plate hole is exactly the draft opening the rule targets. The material does not need to be a listed firestop system in an unrated wall: approved fireblocking materials include mineral wool, unfaced fiberglass batts packed tight, and caulks or foams rated as fireblocking. The orange or red fireblock foams and caulks exist for this use.
Above a panel specifically
A loaded panel often has a dozen or more cables stacked through two or three top plate holes, which makes a large combined opening straight into the attic. Inspectors flag it constantly. Pack or caulk every hole, including the spares. While you are there, confirm the cables are protected per 300.4 and that panel wiring space fill was not the reason the holes got crowded. On the rated garage wall case, use the intumescent product and keep the tube on the truck; the standard gray fireblock sealant is cheap and inspectors know both by color.